It's a demo, and for now it's too simple, it should have something else, like dodge things or having to aim with the gun, bosses maybe? something to make it more fun to play.
(I don't know if your intention was to make a bullet hell game, because this isn't one, if your intention was to make one, then it should have slighlty slower obstacles and more faster movement, look for examples of some of this genre. If your intention wasn't to make a bullet hell, then these tips in parentheses are useless)